Red pimples appear after scratching the arm.

The arm itch scratches after red pimples are more common in urticaria symptoms, urticaria is the skin and mucosa due to temporary vascular permeability increase caused by localized edema. There are many reasons for urticaria, common are internal infection and external contact caused by sensitization environment. Clinically, we should clarify the causes of urticaria, remove the cause and symptomatic treatment. Pruritus can be external antipruritic drugs, such as calamine lotion, compound camphor cream, if necessary, oral antihistamine drugs or vitamin C, etc. The above health science knowledge is for reference only, the specific situation needs to be checked in a regular hospital, judged by a professional doctor.